Glycogen synthase kinase 3 (GSK-3), the well-known target protein for the treatment of diabetes and dementia, is a serine/threonine protein kinase which inhibits the activity of glycogen synthase (GS) by way of phosphorylation.
In the fatty tissue of mice suffering from fatty diabetes, the GSK-3β activity has been observed to be 2 fold higher than that of a normal mouse (H. Eldar-Finkelman, Diabetes, 48:1662–1666 (1999)) and patients during the second type diabetes are characterized by a high expression level of GSK-3β than normal (S. E. Nikoulina et al., Diabetes, 49: 263–171 (2000)). Also, the GSK-3β activity in the brain of a dementia patient is high (Yamaguchi H. et al., Acta. Neuropathol., 92: 232–241 (1996)), and transgenic mice programmed to express GSK-3β in the brain have abnormal neurons caused by hyperphosphorylating tau of the neurofibrillary tangle which plays an important role in the dementia attack (Lucas J. J. et al., EMBO J. 20: 27–39 (2001)).
GSK-3β is further related to bipolar disorder which can be treated by lithium and valproic acid, well-known GSK-3β inhibitors (Elahi S. et al., J. Infect. Dis. 176: 217–226 (1997)).
Thus, there has existed a need to develop an effective inhibitor of GSK-3β for treating or preventing GSK-β-dependent diseases.
The present inventors have endeavored to develop an effective inhibitor of GSK-3β; and have unexpectedly found that a compound containing a hydroxybenzoimidazole carboxylic amide moiety can inhibit the activity of GSK-3β, and therefore, can be used for treating or preventing GSK-β-dependent diseases such as fatness, diabetes and dementia.